Insulating Extrudates from Polyolefin Blends

Abstract

Hollow microspherical, mineral or hard plastic, fillers are used to increase the insulation properties of thermoplastic olefin compositions, especially where used in extruded profiles, sheets or tapes. The thermoplastic olefins comprise a thermoplastic phase and a rubber phase wherein the rubber is at least partially cross-linked by dynamic vulcanization. The microspherical fillers can be added by melt blending with the pre-formed thermoplastic olefins. The natural wear-resistance, oxidative stability and thermal insulating properties of thermoplastic olefins, with the enhancement from the hollow microspheres make them particularly suitable for marine conduits, such as those used in the off-shore drilling industry in flexible pipelines, electrical cables and tethering lines.

Description

FIELD OF INVENTION [0001] The invention relates to microsphere-containing polymer composites suitable for extruded profiles, sheets or tapes for use in industrial articles where flexibility, dimensional and environmental stability, and thermal insulating properties are desired. BACKGROUND OF INVENTION [0002] Hollow glass beads have long been proposed for insulation composites with various resins, see U.S. Pat. No. 4,303,732, U.S. Pat. No. 4,556,603 and U.S. Pat. No. 5,713,974. Polypropylene and polyethylene have been proposed for modification with hollow, glass beads for protective, insulating covers of marine pipelines, see U.S. Pat. No. 5,094,111. Similar composites have been proposed with polypropylene copolymers and blends of those with either of elastomeric styrene-based block copolymers or EPDM rubber in U.S. Pat. No. 5,158,727, the glass beads to comprise from 5 to 70 percent by volume of the composite material. A background discussion of the development of syntactic foam the...

AI Technical Summary

Benefits of technology

[0006] The invention comprises an insulating polymeric extrudate comprising a thermoplastic resin matrix phase having a dispersed phase of at least partially crosslinked rubber; and, hollow microspheres dispersed within the resin matrix phase. The insulating extrudates according to the invention can be prepared by melt blending microspherical, hollow inorganic or extremely hard polymeric fillers with a preformed thermoplastic vulcanizate of the thermoplastic and crosslinked rubber. The thermoplastic can be any engineering resin or blend thereof, polyolefin thermoplastics are preferred. The rubber can be any rubber capable of being dynamically crosslinked, or vulcanized, with ethylene copolymer, particularly EPDM, rubbers being preferred. They can further comprise various amounts of curatives, plasticizers, fillers, etc. The insulating filler is desirably present in amounts of from about 10 to about 45 weight percent of the thermoplastic vulcanizate total composition weight. Functionalization of the thermoplastic phase with functionalization agents and of the surface of the microspheres to enhance the bonding between the two is encompassed as well.

Problems solved by technology

Though both thermoplastic elastomers and syntactic foams using microspheres are widely recognized, there is a prejudice in the art against using TPVs as the thermoplastic elastomers in such a manner.

Additionally, the thermoplastic phase alone in the TPVs, normally comprising a lesser volume content than the rubber phase, would not be expected to be capable of incorporating sufficient microspheres to meet the requirements for the thermal insulation properties sought.